Haven't seen this posted yet. Looks like he'll be out 6 weeks, as the knee injury was less serious than originally thought. From Rotoworld:

Preston Wilson's surgery wasn't as serious as anticipated Monday. Three loose cartilage particles, not a torn meniscus, were the cause of the swelling in his left knee.
The particles were removed and P-Dub is scheduled to begin rehab next week. He's targeting a June 1 return.
Source: Denver Post

I still don't believe Wilson is going to be healthy after that. If you can find some sucker who thinks he's going to return early, trade Wilson right away. I got Vernon Wells for Wilson in one league and Adam Dunn for Wilson in another and I couldn't be happier.